The invention relates to methods and products for neutralizing acid on dermatological surfaces of animals, particularly humans.
In human skin, sebaceous glands, eccrine sweat glands and apocrine glands secrete various chemicals onto the skin surface. These chemicals include sodium chloride, potassium bicarbonate, lactic acid, urea, squalene, proteins, carbohydrates, triglycerides and other lipids. Although body odor may be partially due to certain chemicals secreted by sebaceous glands and eccrine sweat glands, major axillary (underarm) foul odor is due to secretions of the apocrine glands, which contain special nutrient materials for microorganisms.
Apocrine glands are located primarily in the axillae, anal-genital region, mammary areolae, ear canals, eyelids, and are scattered on parts of the face, anterior chest and abdomen. In general, the apocrine duct opens into the upper end of the hair follicle, although the duct occasionally opens directly onto the skin surface. In contrast to the eccrine glands, which produce a clear watery liquid, the apocrine glands secrete a milky fluid that has a pH range of 5 to 6.5 and initially consists of lipids, proteins and carbohydrates. Although fresh apocrine secretions do not have an objectionable odor, the secreted compounds are found to undergo decomposition by both chemical and microbial actions, and the degradation products are responsible for the offensive odors. Chemical substances identified as contributing to this unpleasant odor include lower organic acids such as butanoic, isopentanoic, hexanoic and octanoic acids; mercaptans; indoles; amines; hydrogen sulfide; ammonia; and phosphine. Although gram-positive bacteria, which thrive on substances found on the moist skin surface, appear to be responsible for the production of malodor, the precise mechanisms of odor production are still unclear.
Most deodorant or antiperspirant products on the market today are salts of aluminum, zirconium and/or zinc. The aluminum salts include aluminum chloride, aluminum chlorhydroxide, aluminum sulfate, aluminum potassium sulfate and aluminum phenolsulfonate; the zirconium salts include particularly zirconium oxychlorides and hydroxychlorides; and the zinc salts comprise zinc oxide, zinc peroxide, zinc stearate and zinc phenolsulfonate.
Although long-term use of aluminum, zirconium and/or zinc salts as underarm deodorants presents no major problems in toxicity, these compounds frequently cause irritation, burning, itching or other uncomfortable sensations to individuals with sensitive skin. These individuals may stop using commonly available underarm deodorants because of persistent itching or burning after use. Moreover, such irritation, burning and itching caused by underarm deodorants makes them even less suitable for application to other areas of the body which are even more sensitive than the underarm. Development of other efficacious anti-odorant substances which do not cause irritation or uncomfortable sensation when applied to the skin is therefore desirable.